FIGS. 5A and 5B illustrate a conventional probe apparatus used for inspecting electrical characteristics of, e.g., devices formed on a wafer during the manufacture of the devices. As shown in FIGS. 5A and 5B, the probe apparatus includes a loader chamber 1 for loading a wafer W and a prober chamber 2 for inspecting electrical characteristics of the wafer W conveyed from the loader chamber 1. The loader chamber 1 includes a cassette table 3, a wafer convey mechanism 4 for conveying the wafer W to the prober chamber 2, and a sub-chuck 5 for pre-aligning the wafer W with reference to an orientation flat or a notch thereof during the process of conveying the wafer W via the wafer convey mechanism 4.
Further, the prober chamber 2 includes a temperature controllable main chuck 6 on which the pre-aligned wafer W provided by the wafer convey mechanism 4 is mounted; an XY table 7 which moves the main chuck 6 in X and Y directions; a probe card 8 arranged above the main chuck 6; and a position alignment mechanism 9 which enables a plurality of probe pins 8a of the probe card 8 to be precisely aligned to a plurality of electrode pads (not shown) of the wafer W mounted on the main chuck 6. The alignment mechanism 9 includes an upper camera 9b attached to an alignment bridge 9a to monitor the wafer W and a lower camera 9c attached to the main chuck 6 to monitor the probe pins 8a. The alignment bridge 9a aligns the electrode pads of the wafer W and the probe pins 8a by way of advancing from one end of the prober chamber 2 to a probe center along a pair of guide rails 9d. 
Furthermore, as shown in FIG. 5A, a test head T of a tester is movably disposed on a head plate 2a of the prober chamber 2 and is electrically connected with the probe card 8 via a performance board (not shown). With the temperature of the wafer W on the main chuck 6 being set at a temperature ranging from −20° C. to +150° C., inspection signals are sent from the tester via the test head T and the performance board to the probe pins 8a. The electrical characteristics of a multiplicity of semiconductor elements (devices) formed on the wafer W are inspected by applying the inspection signals from the probe pins 8a to the electrode pads of the wafer W.
The inspection of the wafer includes a high temperature inspection and a low temperature inspection. During the high temperature inspection process, the wafer is inspected after being heated up to a predetermined temperature (e.g., at 100° C. or higher) by a temperature control mechanism embedded in the main chuck 6. The low temperature inspection process is carried out after cooling the wafer down to a predetermined temperature (e.g., at 0° C. or lower) by the temperature control mechanism.
In the high temperature inspection process, however, since the wafer is inspected at a high temperature at 100° C. or higher, the probe card 8 is heated by the main chuck 6 and therefore, may be bent by thermal deformation. As a result, the Z directional distance (Z vertical distance) between the probe pins 8a and the electrode pads of the wafer W can be varied by, e.g., 100 μm, causing poor contacts between the probe pins 8a and the electrode pads of the wafer W and decreasing inspection reliability. Therefore, the main chuck 6 is heated before the inspection and the probe card 8 is preheated by placing the main chuck 6 in proximity to the probe card 8. The wafer is then put into a pseudo-contact state by considering the thermal deformation of the probe card 8 and the actual inspection is performed so that the poor contact problems between the probe pins 8a and the electrode pads can be ameliorated.
However, even in such a case where the probe card 8 is preheated and the wafer W is put into the pseudo-contact state prior to the actual inspection stage, the Z directional displacement of the probe card 8 due to a thermal deformation caused by additional heating during the actual inspection stage and that due to a contact load urged thereto during the inspection stage cannot be properly estimated. Accordingly, an excess or deficiency may occur in the contact load between the probe pins 8a and the electrode pads of the wafer W, to thereby lower the inspection reliability. Furthermore, a considerable amount of time (e.g., 1˜2 hours) may be required for the probe card 8 to become thermally stable, leading to a significant decrease in throughput.